Production of yarns



Sept. 6, 1966 s. FrrToN ETAL 3,270,492

PRODUCTION 0F YARNS Filed Aug. 21, 1962 4 Sheets-Sheet l /A/VE/VTOPSI Flc-,.2

Sept 6. 1966 s. FrrToN ETAL 34,270,492

PRODUCTION OF YARNS Filed Aug. 21, 1962 4 Sheets-Sheet 2 KIS/Mil VAL LAB HDA .S VID l/l/ ZWMMM? Sept- 6 1955 s. FlTToN ETAL 3,270,492

PRODUCTION OF YARNS Filed Aug. 21. 1962 4 Sheets-Sheet 3 @WWYM Sept. 6, 1966 s. FrrToN ETAL PRODUCTION OF YARNS 4 Sheets-Sheet 4 Filed Aug. 21. 1962 vIO 6eme/Pen Damen.

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United States Patent 3,270,492 PRODUCTIGN 0F YARNS Sydney Fitton, Spondon, and Kishan Vallabhdas Vidhani, Arnold, Nottingham, England, assignors to The Hosiery and Allied Trade Research Association Filed Aug. Z1, 1962, Ser. No. 218,338 Claims priority, application Great Britain, Aug. 23, 1961, 30,361/ 61 11 Claims. (Cl. 57-157) This invention relates to improvements in the production lof crimped continuous filament yarns, primarily made of thermoplastic material .such for example as polyamides, polyesters, polyvinyl chloride, acrylonitrile, and cellulose triacetate.

These crimp yarns when produced by twisting, steam setting `and untwisting, by false twisting, by stuifer box crimping, and by edge crimping, are generally characterized by their high degree of contraction from their extended state when the crimp is fully developed, and this imparts to fabrics made from the yarns, properties of high density, high extensibility and firm rigid handle, for which reason they are mainly suitable for certain types of articles such for example as mens half hose, womens stretch hose, and swimwear.

For certain other types of articles such for example as knitted outerwear, underwear, woven fabrics including for example knitted or woven dress fabrics it is desirable that the fabrics should have other characteristics such as low density, some flexibility, good draping properties and attractive handle, for which reason yarns made in the aforesaid manner are not so suitable, and instead these fabrics or articles are desirably made from particular yarns such for example as those known by the registered trademarks Saaba, Crimplene and Agilon D, by which the fabrics or articles have the desired characteristics. These particular yarns attain the desired properties, after being crimped by general methods of twist crimping -or edge crimping, by being subjected to Ia post treatment consisting a first operational step of stretching the crimped yarn to an extent sufficiently to straighten the yarn, a second step of allowing it to contract to a small predetermined extent, and a third operational step of heat setting it in its partially contracted form.

The desired properties possessed by most of the yarns produced in this manner are as follows:

(a) High crimp frequency,

(b) Low amplitude wave form crimp,

(c) Low yarn contraction when the crimp is fully developed (the latter by heat, moisture or both), and

(d) High eective setting temperature.

An object of the invention is to enable yarns having at least some of these desired properties to be produced in improved manner.

The invention provides a process for crimping a continuous filament yarn, primarily of thermoplastic filaments, which c-ompri-ses the successive steps of applying a first molecular-modifying treatment to the yarn, discontinuing or lessening the first treatment, and crimping the yarn with the accompaniment lof a second molecular-modifying treatment.

The invention also provides a process for crimping a continuous filament yarn, primarily of thermoplastic filaments, which comprises the successive steps of applying a first molecular-modifying treatment to the yarn, at least in part setting the yarn in the modified molecular form, -and crimping the yarn with the accompaniment of a second molecular-modifying treatment. Conveniently both modifying treatments are of like type such as both of thermal type, or the two modifying treatments are of dissimilar types such as one of thermal 3,270,492 Patented Sept. 6, 1966 ice type yand the other of chemical type. The process is conveniently continuous with the continuously-trave-lling yarn being subjected to said steps in succession. For each of the two modifying treatments the yarn is traversed through a molecular-modifying zone and between the two modifying treatments the yarn is traversed through another zone.

In the instance of thermal treatment the yarn, between the two modifying treatments, is traversed through a cooling zone, and in the instance of the chemical treatment the chemical agent is removed between the two modifying treatments.

The second modifying treatment is conveniently applied while the yarn is in a crimp-distorted condition, the crimping being conveniently effected by false twisting.

Conveniently the second modifying treatment is applied prior to passage of the yarn through a false twisting device, the twist being stopped between the two modifying treatments. The yarn may travel under predetermined stress f-or a first molecular-modifying treatment, under predetermined stress for a second molecularmodifying treatment, under predetermined stress for a second molecular-modifying treatment, and under predetermined stress through an intermedi-ate zone between the two treatments.

The invention also provides a continuous process for crimping a thermoplastic yarn, which consists in withdrawing the yarn from a wound supply thereof, passing it under la first predetermined stress through a molecularmodifying zone, passing it under a second predetermined stress through a molecular-modifying zone, passing it under -a third predetermined stress through an intermediate and twist stopping zone, subjecting it to a false twisting process, and winding it into a package.

The process may be applied to a flat (i.e. substantially undistorted or twistless) thermoplastic yarn which may be a mono-filament or :a multi-filament yarn.

The invention further provides apparatus for crimping a continuous filament yarn, primarily of thermoplastic filaments, in a continuous process, said apparatus being of a type having means for applying a crimp distortion to the yarn accompanied by Ia molecular-modifying treatment, characterized by means for subjecting the running yarn to a prior treatment consisting of another molecularmodifying treatment. There -are means for guiding the yarn in a path which takes it in a first treatment through molecular-modifying means, in a second treatment through molecular-modifying means and crimp-distorting means, -which may be a false twisting device, and through an intermediate Zone between the two modifying means. There may be twist :stopping means in said intermediate zone. There may be one type of modifying means such as heater means or two types such as heater means and chemical means. Conveniently said intermediate zone is a cooling zone. The rst modifying means may be a chemical swelling agent which is removed at said intermediate zone. The twist .stopping means may be of the type such as tension applying devices, and nip rollers.

Conveniently the heater means is in the form of one of the following types, `means providing a heated surface for contact by the yarn, radiation means, convection means, immersion mean-s and dielectric means; where heater means are used the intermediate zone is a cooling zone provided by one of the following expedients, removing the yarn from the heating zone, or introducing cold gases, cold liquids, or cold surfaces between the two -heater means; and where chemical means are used removal of the chemical swelling agent is accomplished by one of the following methods, rinsing with water, or evaporation.

The invention further provides apparatus for crimping thermoplastic yarn in a continuous process, comprising a false twisting device, means for guiding the yarn in a path which takes it through molecular-modifying means, then through another zone and twist stopping means, next through molecular-modifying means and to the false .twisting device, and means following said device for winding the treated yarn into a wound package.

The invention still further provides a crimped textile multi-filament yarn in which the filaments are made from thermoplastic synthetic material, characterized in that the yarn E.S.S.T. is between 100 C. and 130 C., ythe crimp rigidity is between `and 20%, and that, of the total yarn contraction occurring under load reducing from .1 gram/denier to zero gram/denier, at least occurs substantially in the region of load reduction from .0015 gram/ denier to zero gram/ denier.

The above and other features of the invention set out in the appended claims are incorporated in the constructions which will now be described, as specific embodiments by way of example with reference :to the accompanying drawings in which:

FIGURE 1 is a side sectional View of a first yarn treating arrangement according to the invention.

FIGURE 2 is a similar View of a second yarn treating arrangement according to the invention.

FIGURE 3 is a similar View of a lthird yarn treating arrangement according to the invention.

FIGURE 4 is a similar view of a fourth yarn treating arrangement according to the invention.

FIGURE 5 is a similar view of a fifth yarn treating arrangement according to the invention.

FIGURE 6 is a similar view of a sixth yarn treating arrangement according to fthe invention.

FIGURE 7 is a front view of apparatus for the yarn treating arrangement of FIGURE 1.

FIGURE 8 is a side sectional view of said apparatus.

FIGURE 9 is a graph illustrating the contraction characteristic of yarn made according to the invention.

In all the yarn treating arrangements hereinafter described wit-h reference to the drawings, yarn in its flat state (i.e. substantially undistorted or twistless) -travels a linear path from a supply through a molecular-modifying zone which in this instance is a heating zone, another Zone which in this instance is a cooling zone, a molecularmodifying zone which in this instance is again a heating zone, and through a false twisting device to a take-up package, and provision is made for preventing the false twist present in the yarn in its second heating stage from running back into the yarn in the firs-t heating stage.

Particularly in each illustration there is shown a package F of fiat yarn, the yarn Y, rollers A feeding yarn into heating and twisting zones, a twist stopping and tension device T, molecular modifying treatment means shown as heater means H, a false twist spindle S, guide rollers G, draw-off rollers B taking yarn from the heating and twisting zones, and a yarn take-up package P. It will -be realized, however, that in accordance with the present invention other molecular modifying means (not shown) may be used just as well, such as a swelling bath through which the yarn is passed.

l In the modifica-tion FIGURE 1 the yarn Y is drawn from the package F of fiat (i.e. substantially undistorted or twistless) yarn by feed rollers A, to run in an upwards direction through the heater H, and on leaving the heater y H, the yarn Y passes through a series of guides G, G1, G2

to the twist stopper and tension device T, during which time the yarn is cooled to ambient or nearly ambient temperature. Fromt-he .twist stopper and tension device T it runs, again in an upwards direction, through the heater H, and then runs via a guide G3 and the false twist spindle S through the draw-off rollers B, to the take-up package P. vIn travelling from the twist stopper and tension device T to the draw-ofi rollers B, false twist is inserted and removed.

In t-he second modification FIGURE 2 the yarn Y from the flat yarn package F runs initially through a twist stopper and tension device T', and then travels upwards through the heater H. The yarn then passes via guides G, G1, G2 to the feed rollers A during which time it is cooled to ambient or nearly ambient temperature. From :the feed rollers A the yarn passes again upwards through the heater H, then through the false twist spindle S and the draw-off rollers B to the take-up package P.

In the modification FIGURE 3 two feed rollers A, A1 are employed, the yarn passing first through the feed rollers A then :through the heater H, then through guides G3, G1, to the feed rollers A1 for the cooling stage and lthen from the feed rollers A1' again upwards through the heater H to the false twist spindle S, draw-off rollers B and take-up package P.

In the modification FIGURE 4 the yarn Y passes from the fiat yarn package F, through t-he feed rollers A, through the hea-ter H, and then via guides G1', G4, to the draw-off rollers B thereby `by-passing the false twist spindle S on one side of it. From the draw-off rollers B the yarn returns downwardly, by-passing the false twist spindle S on the other side 'of it, and via guides G5, G6 again passes through the feed rollers A and upwards again through the heater H again to the draw-off rollers B in its passage to the take-up package P., i.e. this time `after passing through false twist spindle S. During passage of the yarn from the heater H via the guides G1', G4, G5, G6 back to the feed rollers A, the yarn is cooled as before.

In the modification FIGURE 5 the yarn Y passes via the feed rollers A and guides G2, G1, first upwards outside the heater H and then downward through the heater H and out to the twist stopper and tension device T. From the twist stopper and tension device T the yarn again passes upwards through the heater H and then through the false twist spindle S to the draw-off rollers B and from there to the take-up package P. The cooling of the yarn takes place during the time when the yarn leaves the heater H after its first passage therethrough and before it re-enters th'e heater H, i.e. where the yarn passes from the heater H through the twist stopper and tension device T and back to the heater H.

In the modification FIGURE 6 two separate heaters H, H1 are employed, the yarn Y passing from the fiat yarn package F, through the feed rollers A and upwards through the first heater H. From this heater H the yarn Y passes further upwards through a twist stopper and tension device T to the second heater H1 through which it passes still further upwards through the false twisting device S and the draw-off rollers B to the take-up package P. The cooling stage is where the yarn passes from the first heater H through the twist stopper and tension device T' to the s'econd heater H1. The feed rollers A and the twist stopper and tension device T may be interchanged.

In any of the modifications the twist stopper and tension device T may be dispense-d with and yarn forwarding roller means may be employedinstead. The percentage difference in rates of feed of the yarn by the different rollers employed may be varied to suit requirements; by way of example, satisfactory results have been obtained by rates of feed from 3% to 5% overfeed of the flat yarn and *1% to -3% underfeed of the twisted yarn.

It will be seen that the requirements of the invention are satisfied in all the modifications by the yarn Y being first heated to molecularly modifyth'e yarn in the fiat state, (i.e. to depart from molecular alignment to a predetermined extent) and also` heated in the crimped state A,to which it is distorted by the false twisting spindle, with an intermediate Zone where the first treatment is discontinued or lessened, or the yarn is at least `in part set in the modified molecular form (i.e. stabilized after the departure from molecular alignment and before heating in the crimped state).

These examples are representative of various ways of carrying the invention into effect in a continuous process. Alternatively, the process may be performed in discrete steps, i.e. the first heat treatment described for any of the different modifications may be performed in one op'eration or machine, and in a separate and subsequent operaion, which may be in a separate machine, the treated yarn may be subjected to any general crimp processing system.

It is to be understood that the false twisting spindle S is representative of the yarn distorting device in any general crimping system in addition to false twisting, e.g. representative of the edge in edge crimping and the stuffer box in stuffer box crimping.

The following are examples of alternative ways of applying the heat to the yarn in the two stages.

(l) Heating the fiat yarn by steam heating (not as shown), and false twisting with dry h'eat.

(2) Heating the flat yarn and false twisting with heat using dry heat at two spaced locations (FIGURE 6).

(3) Heating the `fiat yarn and false twisting with heat at only one location using dry heat (FIGURES 1 to 5).

It is also to be understood that means (not shown) other than heat may be employed for obtaining equivalent molecular modification of the yarn for example as follows:

Swelling the fiat yarn by soaking it in phenol or alcohol and false twisting with heat using dry heat.

It is to be furth'er understood that yarns other than thermoplastic yarns such for example as cellulose yarns may be made by any of the methods herein described suitably modified if necessary such as in the chemical process by using a chemical appropriate to the yarn.

It will be seen that whether -chemical or thermal means are adopted in the first modification of molecular structure the invention provides that either thermal or chemical means may be used in the second, i.e. that which occurs when the yarn is undergoing the crimping process. The heat setting of the yarn in either its flat state or its crimp distorted state may be by direct contact with a hot surfac'e; by radiation or convection means; by immersion in some suitable fluid or gas; by dielectric means or by any other heating means. Cooling, after the first thermal treatment, may be accomplished by removal of the yarn from the heating zone, or by introduction of cold gases, liquids or surfaces between the two heater means. The chemical modification of the yarn in either its fiat `state or in its crimp distorted state may be accomplished by any `suitable swelling agent appropriate to the yarn material. Removal of the swelling agent after the first stage rnay be accomplished by rinsing with water or by evaporation. Twist stopping means may be provided by nip rollers or by suitable arrangements of contacting surfaces such as are 4found in many tension applying devices, e.g. in tension gates.

In the examples of some results appertaining by way of example to polyamide and polyester yarns which will be hereinafter fully described, reference will be made to the E.S.S.T. (equivalent steam `setting temperature) of the yarns which may be defined as the temperature of saturated steam which must be exceeded before the yarn begins to shrink; it is also a measure of the effective heat treatment which a yarn has received.

It should here be explained that a study of the phenomenon of heat setting in nylon 66, nylon 6 and Terylene yarns and fabrics has led to a residual shrinkage testing technique by which the E.S.S.T. (equivalent steam setting temperature) of any of these yarns may be determined. For full details in connection with the E.S.S.T. of yarn,vsee Journal of the Textile Institute, Munden, D. L. and Slater, D., June 1959, vol. 50, T393-T403, and British Standards Handbook No. 11, 1963, pages In the crimping of thermoplastic yarns such as those mentioned above, it has been observed that the extent to which the crimping deformation imposed is retained after setting, depends on the temperature of the setting process.

Further it can be observed in the heating setting of fabrics ma-de from such thermoplastic yarns, and in the post treatment of such yarns as previously mentioned, that the extent to which deformation is retained after setting (or in the latter case the extent to which deformation is removed after setting) depends on th'e effective difference of temperature between the first and second heating setting operations.

The effectiveness of setting thermoplastic yarns by dry heat and steam being non-equivalent, it is convenient in the present examples of polyamide and polyester yarns to use the E.'S.S.T. of the yarn as a measure of effective heat treatment. A study of post treated false twist and edge crimped yarns, which have -found acceptance in outerwear, underwear and woven fabrics indicates that some of the desirable properties of such yarns may be listed as:

(l) The highest degree of filament `separation (bulk) comparable with a low potential yarn contraction.

(2) A high crimp frequency to ensure a clear stitch structure.

(3) A high E.S.S.T. to enable such processes as fabric setting and yarn dyeing to be performed with minimum loss of yarn crimp and fabric handle.

In the normal production of a false-twist nylon 66 yarn a fiat yarn with an E.S.S.T. in the region 40e50 C. is used.

The E.S.S.T. of the crimped yarn is 'in the region of 10G-120 C. Thus the crimp is imposed with a difference in E.S.S.T. of some 60-70 C.

In the yarn process described in the invention a similar deformation is imposed with lesser difference in E.S.S.T. which may be of the order 15-30 C. and the retained deformation is much less.

The lower differential is obtained by heating the yarn before the false-twist process as distinct from the post treating method which incorporates partial development of crimp and heating setting after the false-twist process. The theory is, of course, applicable to all the aforementioned alternative methods of crimping yarn. In this respect, it should be noted that in the examples concerned with the embodiments of FIGS. 1 and 3-6 shrinkage of the yarn, as a natural result of the heat treatment before the false twist step, is .in fact permitted to take place because of the overfeed of the yarn. In the example concerned with the embodiment of FIG. 2 the shrinkage is permitted to take place in spite of the underfeed of yarn because of the tension gates which allow yarn to be drawn therethrough in consequence of the shrinking action of such yarn.

Examples hereinbefore referred to of some results are as follows for nylon 66 yarns:

(a) Pre-heat treatment by steam: Separate dry heat false-twist; false-twist conditions: t.p.i.: 198 C. heater plate temperature and 3% ovcrfeed:

E.S.S.T. in C. of Flat Yarn Percent Crimp E.S.S.T.in C.

Rigidity 1 0f inal Yarn 8. 5 100 C.i5 C.

1 Crimp Rigidity is the percentage yarn extended state when measured in water at weights and tensions.

(bank) contraction from the 20 C.;l:2 C. using specified (b) False-twist conditions as in (a) above.

E.S.S.T. in C. of E.S.S.'I.in C. Percent Crimp E.S.S.T.in C. Untreated fiat yarn of Phenol Rigidity of Final Yarn Soaked Yarn 48 70 15. 0 100 C.;i;5 C.

(c) Pre-heat treatment by dry heat: separate dry heat false-twist: false-twist conditions: 80 t.p.i.:3% overfeed at each stage: 235 C. heater plate temperature at each stage.

E.S.S.T. in C. 01' Flat Yarn E.S.S.T.inC.

Percent Crimp Final Yarn Rigxdity (d) Pre-heat treatment by dry heat and dry heat falsetwist as continuous process. Conditions 80 t.p.i.: 1%

An embodiment of the invention using the edge crimping process gave the following results:

Normal edge-crimped yarn gave a crimp rigidity of about 30% on the fully bulked yarn, -i.e. yarn bulked in hank form in water at 85 C. whereas the pre-heat treated edge crimped yarn gave a crimp rigidity of about 12% on yarn similtrly bulked at 85 C.

An embodiment of the invention using the stuifer box crimping system gave the following results:

Normal stuffer box crimp yarn gives a crimp rigidity of about 15% whereas the pre-heat treated stutter box crimped yarn gave a crimp rigidity of about 10%.

Yarns produced by these methods are characterized by having a high effective yarn setting temperature, high crimp frequency, a low yarn contraction when in fabric form, and a high degree of lament separation for a given amount of yarn contraction.

Fabrics made from the yarns are consequently characterized by a very soft handle, by good recovery from extension, and a high degree of cover from a given yarn denier and stiffness of fabric construction.

These results are obtained principally by virtue of the fact that the cooling zone, or its equivalent zone, allows the yarn to become established, or stabilized, or at least in part set in the molecular modified state (of departure from molecular alignment) resulting from the rst molecular modifying treatment and shrinkage by the bonding together of the molecules in a dilferent arrangement (of departure from molecular alignment) while they are no longer in a state of flux.

Examples of nylon 66 yarns illustrating a particular contraction feature are as follows:

(a) A torque crimped textile multi-filament yarn in which the filaments are made from thermoplastic synthetic material is characterized by having an E.S.S.T. of between 100 C. and 130 C., the crimp rigidity is between 5% and 20% and that after fully developing the crimp by hot water treatment of the yarn in hank form at 50 C. the percentage of contraction of the yarn from its fully extended state (i.e. when loaded to 0.1 gram/ denier) is between 40% and 55% at a load of 0.0015 gram/ denier and between 65% and 80% at a load of zero 'grams/ denier.

(b) An edge crimped textile multi-iilament yarn in which the laments are made from thermoplastic synthetic material is characterized in that the yarn E.S.S.T. is between 100 C. and 130 C., the crimp rigidity of the fully bulked yarn is between 5% and 20% and that, after fully developing the crimp by hot water treatment at 50 C. of the yarn in hank form, the percentage of contraction of the yarn from its fully extended form (i.e. when loaded to 0.1 gram/denier) lies between 17% and 23% at aload of 0.01015 gram/denier and 24% and 30% at a load of zero grams/denier.

(c) A stuffer box crimped textile multi-filament yarn in which the laments are made from thermoplastic synthetic material is characterized in that the yarn E.S.S.T. is between 100 C. and 130 C., the crimp rigidity between 5% and 13% and that, after fully developing the crimp by hot Water treatment at 50 C. of the yarn in hank form, the percentage of contraction of the yarn from its fully extended state (i.e. when loaded to 0.1 gram/ denier) lies between 12% and 17% at a load of 0.0015 gram/denier and between 19% and 24% at a load of zero grams/denier.

In these examples, of the total yarn contraction occurring upon load reducing from 0.1 gram/denier to zero grams/denier, at least 20% occurs substantially in the region of load reduction from .0015 grarn/ denier to zero grams/ denier.

A tabulated example of this in comparison with a known yarn of like type is given as follows and is illustrated in graph form in FIGURE 9:

Yarn according Known false Grams/denier to invention twist yam (C.R. 15%) (C.R. 32%) l 24% Difference i.e. 34%

of total approx. 2 12% Difference i.e. 16%

of total approx.

It will be seen that whereas for the known yarn the percentage difference of contraction between the loads of .0015 gram/denier and zero grams/denier is 12% being approximately 16% of the total contraction, that for this particular yarn according to the invention is 24% being approximately 34% of the total contraction. In all other examples according to the invention of nylon 66 yarn it is found that the percentag of the total contraction under similar circumstances is at least 20%.

It is an advantage of the invention that it can be carried out on existing multi-unit crimping machines with onlgr minor machine modifications such for examples as to yarn guides and tension devices.

A particular advantage of the use of the single heater arrangements in a multi-unit machine is that, whereas there may be variations in applied heat at the different twisting station-s in the machine, it is the differential in effective heat (there being a differential by virtue of the contrasting Iiiat and twisted states of the yarn) between the two stages at each twisting station which determines the crimp characteristics, and this differential will be substantially constant for all the twisting stations, so that the crimp will be substantially regular for all the twisting stations.

This machine adaptation is illustrated in FIGURES 7 and 8 which shows an existing multi-unit false twisting machine modified by way of example according to the modification of FIGURE 1.

Briefly there is a support frame 1, a base 2 mounting yarn packages F, brackets 3 carrying the feed rollers A, a pair of bus bars 4, S carrying heaters H, an angle iron support 6 for false twisting spindles S, a bracket 7 for draw-0E rollers B, and bracket supports P1 for the takeup packages P. As aforesaid, the heaters H may also take the form of a different molecular modifying means (not shown), such as a container having a liquid swelling bath therein through which the yarn is passed.

An electric driving motorl 8 is carried by the frame 1 and it drives a large pulley 9 driving `a belt 10 one lap of which engages and drives the false twist spindles S. The belt 10 also drives another large pulley 11 which imparts drive through reduction gear means 12 -to a lower spindle 13 carrying drive rollers A1 (FIGURE 1) for driving the feed rollers A. The pulley 1,1 (FIGURE 7) further drives, through reduction gear means 14 an upper spindle 15 carrying drive rollers B1 (FIGURE 1) for driving the feed rollers B, and the pulley 11 (FIGURE 7) still further drives, through reduction gear means 16 an upper spindle 17 carrying rollers P2 for driving the take-up packages I.

In this example twist stopper and tension devices T are of adjustable gate type mounted on a support rod 18 which also carries the guides GZ (FIGURE 1), the other guides G, G1, G3 being mounted on the heater H.

The heater H in this example is of electric resistance type having electric resistance H2 (see FIGURE 1) with a suitable control device H3, and a thermostat H4, which together are connected to the bus bars 4, 5. The latter are connected to a suitable control unit 19 (FIGURES 1 and 7, 8) having a suitable manual control 20 and connected to mains lines M.

It will be seen that this machine is readily adapted for any of the other modications of FIGURES 2 to 6 in a manner presenting no difculties to those skilled in the art and therefore not being herein described in detail.

Similarly it will be understood that other modifications hereinbefore referred to may be readily carried out either on the illustrated machine or on other known machines in a manner presenting no difficulties to those skilled in the art and therefore not being herein particularly described.

What we claim is:

1. A process for crimping a thermoplastic filament, which comprises the sequential steps of submitting the filament to a shrinking treatment in which the molecular structure of the filament is modified, stabilizing the filament in its molecularly-modified condition, submitting the filament to a second molecularly-modifying treatment and physically distorting the filament to impart a crimp thereto.

2. A process for crimping a thermoplastic filament comprising the sequential steps of submitting the filament to a molecularly-modifying heat treatment, feeding the filament where it is subjected to said heat treatment at an overfeed rate permitting the filament to shrink, stabilizing the filament by cooling it in its modified condition, submitting the filament to a second molecularly-modifying treatment and physically distorting the filament to impart a crimp thereto.

3. A process for crimping a thermoplastic filament comprising the `sequential steps of submitting the filament to a molecularly-modifying heat treatment, pulling the filament where it is being subjected to said heat treatment through a yarn tension device at a selected rate permitting shrinking of the filament, stabilizing the filament by cooling it in its modified condition, submitting the filament to a second molecularly-modifying treatment and physically distorting the filament to impart a crimp thereto.

4. A process for crimping a filament comprising the sequential steps of shrinking the filament in a first molecularly-modifying treatment to modify the molecular structure of the filament, stabilizing the filament in its modified condition, submitting the filament to a second molecularlymodifying treatment, physically distorting the filament by false twisting the filament, and stopping the false twist from running back into the filament in the first molecularly-modifying treatment.

5. A process for crim-ping a filament comprising the sequential steps of swelling the filament in a first molecularly-modifying treatment using a chemical swelling agent to modify the molecular structure of the filament and to permit shrinking thereof, stabilizing the filament in its modified condition by removing the swelling agent, submitting the filament to a second molecularly-modifying treatment to further modify the molecular structure of the filament and physically distorting the filament to impar a crimp thereto.

6. A process for crimping a nylon filament comprising the -sequential steps of shrinking the filament in la first heat treatment by steam heating the filament while feeding the filament at an overfeed rate, stabilizing the filament by cooling it in its modified condition, physically distorting the filament in a second heat treatment lby dry heating the filament while imparting a false twist to the heated filament, and stopping the false twist from runn-ing back into the filament in the first heat treatment.

7. A process for crimping a nylon filament comprising the sequential steps of shrinking the filament in a first heat treatment by dry heating the filament at a selected temperature while feeding the filament at an overfeed rate, stabilizing the filament by cooling it in its modified condition, physically distorting the filament in a second heat treatment by dry heating the filament at the same temperature used in the first heat treatment while imparting a false twist to the heated filament and continuing to feed the filament at said overfeed rate, and stopping the false twist from running back into the filament in the first heat treatment.

8. A method of crimping a nylon filament in a continuous process comprising shrinking the filament in a first heat treatment by dry heating the filament while feeding the filament at a selected rate, stabilizing the filament by cooling it in its modified con-dition, physically distorting the filament in ia second heat treatment by ldry heating the filament while imparting a false twist to the heated filament, and stopping the false twist from running back into the filament from the first heat treatment.

9. A process for crimping a thermoplastic filament comprising the sequential steps of shrinking the filament in a molecularly-modifying treatment to modify the molecular structure -of the filament, stabilizing the filament in its modified condition, and edge crimping the filament by passing the filament `against .an edge to impart a crimp to the filament.

10. A process for crimping a filament comprising the sequential steps of submitting the filament to a molecularly-modifying treatment to modify the -molecular structure of the filament and to permit shrinking thereof, stabilizing the filament in its modified condition, and stuffer box crimping the filament by passing the filament through a stuffer box to impart a crimp to the filament.

11. In a process for crimping a filament comprising the sequential steps of submitting the filament to a first molecularly modifying treatment, lsubmitting the filament to a second molecularly modifying treatment and physically distorting the filament to impart a crimp thereto, the improvement which comprises submitting the filament to first molecular modifying treatment to obtain predetermined ydeparture from molecular alignment in the filament and stabilizing the filament in its molecularly modified condition before subjecting the filament to the second molecularly modifying treatment and crimp imparting physical distortion.

References Cited by the Examiner UNITED STATES PATENTS 2,475,922 7/ 1949 Stockly 57-34 3,028,653 4/1962 Evans 57-34 3,041,814 7/1962 Held 57-34 3,067,563 12/1962 Van Dijk 5734 3,085,389 4/1963 Wegener et al. 57-34 3,114,235 12/1963 Griset 57-157 3,115,744 12/1963 Nott 57-157 3,137,119 6/1964 Crouzet 57-34 X 3,142,951 8/1964 Terra 57--34 3,152,435 10/1964 Pittman et al. -57-140 3,154,906 11/ 1964 Assendelft et al. 57-34 3,157,022 11/1964 Haynes 57-140 3,165,881 1/ 1965 Moncuit et al 57-34 3,167,383 1/1965 Ohezaud et al. 28-72 X FOREIGN PATENTS 1,260,295 3/ 1961 France.

MERVIN STEIN, Primary Examiner. H. G. GARNER, D. E. WATKINS, Assistant Examiners.

RUSSELL C. MADER, Examiner. 

1. A PROCESS FOR CRIMPING A THERMOSPLASTIC FILAMENT, WHICH COMPRISES THE SEQUENTIAL STEPS OF SUBMITTING THE FILAMENT TO A SHRINKING TREATMENT IN WHICH THE MOLECULAR STRUCTURE OF THE FILAMENT IS MODIFIED, STABILIZING THE FILAMENT IN ITS MOLECULARLY-MODIFIED CONDITION, SUBMITTING THE FILAMENT TO A SECOND MOLECULARLY-MODIFYING TREATMENT AND PHYSICALLY DISTORTING THE FILAMENT TO IMPART A CRIMP THERETO. 